I use a GPG key to sign my git commits.
An error like this one might be a sign of an expired GPG key.
error: gpg failed to sign the data fatal: failed to write commit object
No need for homebrew or anything like that. Works with https://www.git-tower.com and the command line.
gpg --list-secret-keys
and look for sec
, use the key ID for the next stepgit
to use GPG -- replace the key with the one from gpg --list-secret-keys